It may not be the fastest, but something like Common Lisp has extensive numeric capabilities built-in like computing with floats, bignums, complex, ratios, ... Extensive mathematical software has been written in Lisp like Reduce (written in Standard Lisp), Macsyma, Axiom, ... In education for a while something like Derive, MuSimp/MuMath, ... was used. Derive should also have been used in pocket calculators, which would be in the spirit of Lisperati1000.